Putter head

ABSTRACT

A putter ( 100 ) having a club head ( 20 ) having a central aperture ( 32 ) with a rearward center of gravity is disclosed herein. The club head ( 20 ) has a body ( 22 ) that is preferably composed of stainless steel. The body ( 22 ) has a face portion ( 24 ), a crown portion ( 26 ), a sole portion ( 28 ) and an aft-mass portion ( 30 ). The face portion ( 24 ), the crown portion ( 26 ), the sole portion ( 28 ) and the aft-mass portion ( 30 ) define the central aperture ( 32 ). The crown portion ( 26 ) extends rearward from the face portion ( 24 ) over the aft-mass portion ( 30 ). The central aperture ( 32 ) separates the crown portion ( 26 ) from the sole portion ( 28 ) and the face portion ( 24 ) from the aft-mass portion ( 30 ). The crown portion ( 26 ) has an alignment means ( 40 ) thereon for aiming a golf ball during putting. The putter has novel inertial properties.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation-in-part application ofco-pending U.S. patent application No. 10/063,908, filed on May 22,2002, which is a continuation-in-part application of co-pending U.S.patent application No. 09/683,125, filed on Nov. 21, 2001, which is acontinuation-in-part application of co-pending U.S. patent applicationNo. 29/147,888, filed on Sep. 7, 2001, now U.S. Pat. No. D458,656 and acontinuation-in-part of co-pending U.S. patent application No.09/693,349, filed on Oct. 20, 2000, which is a divisional application ofU.S. patent application No. 09/389,798, filed on Sep. 3, 1999, now U.S.Pat. No. 6,238,302.

FEDERAL RESEARCH STATEMENT

[0002] Not Applicable

BACKGROUND OF INVENTION

[0003] 1. Field of the Invention

[0004] The present invention relates to a putter-type club head. Morespecifically, the present invention relates to a putter-type club headhaving a rearward center of gravity.

DESCRIPTION OF THE RELATED ART

[0005] The golf industry has been inventing putters that make the gameof golf easier for the high handicap player. One such putter isdisclosed in U.S. Pat. No. 4,688,798 to David Pelz. The Pelz patentdiscloses a putter with an alignment means to assist a golfer in aiminga golf ball toward a hole during putting. The Pelz patent disclosesusing two or three golf ball shaped indicators as the alignment means.The golf ball shaped indicators may be circles, hemispheres, or completespheres. The Pelz patent discloses positioning the indicators along aline extending rearward from the center of percussion.

[0006] Another patent that discloses an alignment means is U.S. Pat. No.4,659,083 to Szczepanski. The Szczepanski patent discloses a group oflines that converge toward the center of the face of the putter.

[0007] Yet another patent that discloses an alignment means is GreatBritain Patent Application Number 4,659,083 to Lilley. The Lilley patentalso discloses a group of lines that converge toward the center of theface of a putter.

[0008] Although these inventions have provided new and improved puttersfor making the game of golf more enjoyable for high handicap players,the prior art has not optimized a putter by making it more forgiving andassisting in alignment.

SUMMARY OF INVENTION

[0009] One aspect of the present invention is a putter with novelinertial properties.

[0010] Another aspect of the present invention is a putter having a clubhead, a shaft connected the club head, and a grip attached to shaft. Theputter has a center of gravity located at least 1.5 centimeters rearwardfrom a shaft axis of the putter.

[0011] Yet another aspect of the present invention is a putter having aclub head, a shaft connected the club head, and a grip attached toshaft, and the putter has a torsion swing inertia, Ixz, that has anabsolute value greater than 10,000 grams-centimeter square.

[0012] Yet another aspect of the present invention is a putter having aclub head, a shaft connected the club head, and a grip attached toshaft, and the putter has a swing static imbalance, Sy, greater than 500grams-centimeter.

[0013] Having briefly described the present invention, the above andfurther objects, features and advantages thereof will be recognized bythose skilled in the pertinent art from the following detaileddescription of the invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0014]FIG. 1 is a top perspective view of a putter-type club head.

[0015]FIG. 2 is a top perspective view from the heel of the putter-typeclub head of FIG.

[0016]FIG. 3 is a perspective view from the bottom of the putter-typeclub head of FIG. 1.

[0017]FIG. 4 is a top plan view of the putter-type club head of FIG. 1.

[0018]FIG. 5 is a bottom plan view of the putter-type club head of FIG.1.

[0019]FIG. 6 is a front plan view of the putter-type club head of FIG.1.

[0020]FIG. 7 is a rear plan view of the putter-type club head of FIG. 1.

[0021]FIG. 8 is a heel side view of the putter-type club head of FIG. 1.

[0022]FIG. 9 is a toe side view of the putter-type club head of FIG. 1.

[0023]FIG. 10 is a top perspective view of an alternative embodiment ofa putter-type club head.

[0024]FIG. 11 is a top plan view of putter-type club head of FIG. 10.

[0025]FIG. 12 is a bottom plan view of putter-type club head of FIG. 10.

[0026]FIG. 12A is a bottom plan view of putter-type club head of FIG. 10with an alternative sole.

[0027]FIG. 13 is a front plan view of putter-type club head of FIG. 10.

[0028]FIG. 14 is a rear plan view of putter-type club head of FIG. 10.

[0029]FIG. 15 is a heel side view of putter-type club head of FIG. 10.

[0030]FIG. 16 is a toe side view of putter-type club head of FIG. 10.

[0031]FIG. 17 is a cross-sectional view along line 8-8 of theputter-type club head of FIG. 10.

[0032]FIG. 18 is a front plan view of a putter.

[0033]FIG. 19 is a side view of the putter of FIG. 18.

[0034]FIG. 20 is a front plan view of a putter.

[0035]FIG. 21 is a side view of the putter of FIG. 20.

DETAILED DESCRIPTION

[0036] As shown in FIGS. 1-8, a putter-type club head is generallydesignated 20. The club head 20 has a body 22 that is preferablycomposed of a cast metal. A preferred metal for the body 22 is stainlesssteel. Alternative materials for the body 22 include titanium, titaniumalloys, carbon steel, bronze, and the like. The body 22 preferablyweighs from 275 grams to 400 grams, more preferably from 300 grams to350 grams, even more preferably from 315 grams to 335 grams, and mostpreferably 328 grams.

[0037] The body 22 has a face portion 24, a crown portion 26, a soleportion 28 and an aft-mass portion 30. The face portion 24, the crownportion 26, the sole portion 28 and the aft-mass portion 30 define acentral aperture 32 that extends through the body 22. The centralaperture 32 has a heel opening 34 at a heel end 23 of the body 22 and atoe opening 36 at a toe end 25 of the body 22. The central aperture 32horizontally separates the face portion 24 from the aft-mass portion 30,and the central aperture 32 vertically separates the crown portion 26from the sole portion 28. The central aperture 32, in connection withthe aft-mass portion 30, allows for the center of gravity of the clubhead 20, CG, to be moved rearward from the face portion 24. In apreferred embodiment, the CG of the club head 20 is positioned withinthe central aperture 32, and thus the CG is not positioned withinmaterial of the club head 20. Instead, the CG lies outside the club headmaterial in the space within the central aperture 32. Preferably, the CGis located between 0.25 inch and 1.0 inch from an external surface 71 ofthe sole portion 28, more preferably 0.50 inch to 0.75 inch, and mostpreferably 0.73 inch from the external surface 71 of the sole portion28. Also, preferably the CG of the club head 20 is located 0.50 inch to2.5 inches rearward from the external surface 58 of the face portion 24,more preferably 0.75 inch to 1.5 inches, and most preferably 0.944 inchfrom the external surface 58 of the face portion 24. In addition toassisting in the rearward positioning of the CG, the aft-mass portion 30is a rearward support structure for crown portion 26. The aft-massportion 30 extends upward and rearward from a rearward end 29 of thesole portion 28. The aft-mass portion 30 ranges from 10 to 30 volumepercent of the body 22 and ranges from 25 to 75 weight percent of thebody 22. More preferably, the aft-mass portion 30 ranges from 15 to 25volume percent of the body 22 and ranges from 40 to 60 weight percent ofthe body 22. The external surface 64 of the aft-mass portion 30preferably defines an acute edge 65 (relative to the ground) and astraight edge 67 (relative to the ground). As shown in FIG. 3, theaft-mass portion 30 extends outward from the sole portion 28. Aninternal surface 62 of the aft-mass portion 30 defines a portion of thecentral aperture 32.

[0038] The sole portion 28 preferably has an approximate T-shape. Theexternal surface 71 of the sole portion 28 contacts the ground when theclub head 20 is used with a shaft and grip, both not shown, as a putter.A center section of an internal surface 56 of the sole portion 28partially defines the central aperture. The CG of the club head 20preferably lies above the sole portion 28.

[0039] The crown portion 26 extends rearward from the face portion 24.The crown portion 26 has a central elongated section 44 and a frontsection 46. The front section 46 has a width w′ that extends from theheel end 23 to the toe end 25 of the face portion 24, and graduallynarrows as the front section 46 transitions into the central elongatedsection 44. The width, w′, preferably ranges from 2.5 inches to 5.0inches, more preferably from 3.5 inches to 4.5 inches, and mostpreferably 4.25 inches. The central elongated section 44 has a width w″that is less than the width w″ of the front section 46. The width, w″,preferably ranges from 1.0 inch to 3.0 inches, more preferably from 1.5inches to 2.25 inches, and most preferably 1.8 inches. The internalsurface 48 of the crown portion 26 partially defines the centralaperture 32. The crown portion preferably has a thickness that rangesfrom 0.10 inch to 0.50 inch, more preferably 0.15 inch to 0.30 inch.

[0040] The external surface 38 of the crown portion 26 preferably has analignment means 40 thereon. The external surface 38 also preferably hasa cylindrical rod 54 extending upward therefrom for engagement with ashaft, not shown. A preferred alignment means 40 is first and secondcircular inserts 40 a and 40 b disposed within first and second recesses42 a and 42 b in the crown portion 26. The depth of each of the recesses42 a and 42 b is preferably within 0.05 inch to 0.50 inch, morepreferably 0.1 inch to 0.250 inch. Each of the circular inserts 40 a and40 b preferably have a thickness ranging from 0.05 inch to 0.50 inch,more preferably 0.1 inch to 0.250 inch.

[0041] In a preferred embodiment, each of the circular inserts 40 a and40 b are preferably composed of a thermosetting polyurethane materialsuch as described in U.S. Pat. No. 6,273,831, entitled Golf Club Headwith A Polymer Insert, assigned to Callaway Golf (the assignee of thePresent Application), which is hereby incorporated by reference in itsentirety. Alternatively, each of the circular inserts 40 a and 40 b maybe composed of a thermoplastic polyurethane. Each of the circularinserts 40 a and 40 b is preferably colored white, through painting ordoping of the polyurethane with coloring agents, and each circularinsert 40 a and 40 b preferably has a texture of a golf ball cover. Eachof the circular inserts 40 a and 40 b preferably has a diameter rangingfrom 1.62 inches to 1.70 inches, and most preferably 1.68 inches. Thoseskilled in the art will recognize that more than two circular inserts 40a and 40 b may be utilized without departing from the scope and spiritof the present invention. Alternative alignment means are disclosed inU.S. Pat. No. 4,688,798, entitled Golf Club And Head Including AlignmentIndicators, assigned to the Callaway Golf (the assignee of the PresentApplication), which pertinent parts are hereby incorporated byreference. As disclosed in U.S. Pat. No. 4,688,798, the alignment meansassists a golfer in properly aiming a golf ball toward a hole whenputting. Alternative alignment means, including a large white strip maybe utilized in the present invention.

[0042] The face portion 24 preferably has a thickness ranging from 0.10inch to 0.50 inch, more preferably 0.20 inch to 0.35 inch. The faceportion 24 has an internal surface 60 that partially defines the centralaperture 32. The external surface 58 of the face preferably has a facerecess 52 therein with a face insert 50 disposed therein such asdisclosed in U.S. Pat. No. 6,238,302, entitled A Golf Club Head With AnInsert Having Integral Tabs, assigned to Callaway Golf (the assignee ofthe Present Application), which is hereby incorporated by reference inits entirety. As disclosed in U.S. Pat. No. 6,238,302, the face insertis preferably composed of a thermosetting polyurethane material and ispreferably colored white. In an alternative embodiment, the face portion24 is a non-insert blade as is known in the art.

[0043] The body 22 preferably has a length, L, from the face portion 24to the rearward most end of the aft mass portion 30 preferably rangingfrom 2.5 inches to 4.5 inches, more preferably from 3.0 inches to 4.0inches, and most preferably 3.43 inches. In one alternative embodiment,the body 22 has a length, L, that is equal to the width, w′.

[0044] As mentioned previously, the central aperture 32 is defined bythe internal surface 60 of the face portion 24, the internal surface 48of the crown portion 26, the internal surface 56 of the sole portion 28and the internal surface 62 of the aft-mass portion 30. The distancefrom the internal surface 48 of the crown portion 26 to the internalsurface 56 of the sole portion 28 preferably ranges from 0.01 inch to1.50 inches, more preferably 0.25 inch to 1.0 inch, and most preferably0.5 inch. The distance from the internal surface 60 of the face portion24 to the internal surface 62 of the aft-mass portion 30 preferablyranges from 1.0 inch to 3.50 inches, more preferably from 1.5 inches to3.0 inches, and most preferably 2.00 inches. The body 22 is preferablyformed as a single cast structure using known investment castingtechniques. However, those skilled in the pertinent art will recognizethat alternative forming techniques such as milling, welding forged orformed pieces, and the like may be utilized without departing from thescope and spirit of the present invention.

[0045] The golf club putter of the present invention may alternativelyhave an embodiment as shown in FIGS. 10-17, wherein a putter-type clubhead of the present invention is generally designated 20. The club head20 has a body 22 that is preferably composed of a cast metal. Apreferred metal for the body 22 is stainless steel. Alternativematerials for the body 22 include titanium, titanium alloys, carbonsteel, bronze, and the like. The body 22 preferably weighs from 275grams to 400 grams, more preferably from 300 grams to 350 grams, evenmore preferably from 315 grams to 335 grams, and most preferably 328grams.

[0046] The body 22 has a face portion 24, a crown portion 26, a soleportion 28 and an aft-mass portion 30. The face portion 24, the crownportion 26, the sole portion 28 and the aft-mass portion 30 define acentral aperture 32 that extends through the body 22. The centralaperture 32 has a heel opening 34 at a heel end 23 of the body 22 and atoe opening 36 at a toe end 25 of the body 22. The central aperture 32horizontally separates the face portion 24 from the aft-mass portion 30,and the central aperture 32 vertically separates the crown portion 26from the sole portion 28. The central aperture 32, in connection withthe aft-mass portion 30, allows for the center of gravity of the clubhead 20, CG, to be moved rearward from the face portion 24. In apreferred embodiment, the CG of the club head 20 is positioned withinthe central aperture 32, and thus the CG is not positioned withinmaterial of the club head 20. Instead, the CG lies outside the club headmaterial in the space within the central aperture 32. Preferably, the CGis located between 0.25 inch and 1.0 inch from an external surface 71 ofthe sole portion 28, more preferably 0.50 inch to 0.75 inch, and mostpreferably 0.615 inch from the external surface 71 of the sole portion28. Also, preferably the CG of the club head 20 is located 0.50 inch to2.5 inches rearward from the external surface 58 of the face portion 24,more preferably 0.75 inch to 2.0 inches, and most preferably 1.2 inchesfrom the external surface 58 of the face portion 24. In addition toassisting in the rearward positioning of the CG, the aft-mass portion 30is a rearward support structure for crown portion 26. The aft-massportion 30 extends upward and rearward from a rearward end 29 of thesole portion 28. The aft-mass portion 30 ranges from 10 to 30 volumepercent of the body 22 and ranges from 25 to 75 weight percent of thebody 22. More preferably, the aft-mass portion 30 ranges from 15 to 25volume percent of the body 22 and ranges from 40 to 60 weight percent ofthe body 22. The external surface 64 of the aft-mass portion 30preferably defines an acute edge 65 (relative to the ground) and astraight edge 67 (relative to the ground). As shown in FIG. 12, theaft-mass portion 30 extends outward from the sole portion 28. Aninternal surface 62 of the aft-mass portion 30 defines a portion of thecentral aperture 32.

[0047] The sole portion 28 preferably has an approximate semi-circularshape and is substantially planar. The external surface 71 of the soleportion 28 contacts the ground when the club head 20 is used with ashaft and grip, both not shown, as a putter. A center section of aninternal surface 56 of the sole portion 28 partially defines the centralaperture 32, and such center section of the internal surface 56, iscovered by the crown portion 26. A heel section 56 a and a toe section56 b of the internal surface 56 of the sole portion 28 are not coveredby the crown portion, and are exposed as shown in FIG. 11. The CG of theclub head 20 preferably lies above the sole portion 28.

[0048] In an alternative sole embodiment shown in FIG. 12A, the soleportion 28 has a medial ridge 81 along the center of the sole portion 28that is connected to an arc-heel ridge 83 a and an arc-toe ridge 83 b ata juncture 87. A front ridge 82 is perpendicular to the medial ridge 81and is connected to the arc-heel ridge 83 a at one end and the arc-toeridge 83 b at the other end of the front ridge 82. The medial ridge 81,the front ridge 82 and the arc-heel ridge 83 a define a heel recess 85 ahaving a surface 71 a. The medial ridge 81, the front ridge 82 and thearc-toe ridge 83 b define a toe recess 85 b with a surface 71 b. Fromthis bottom view, the medial ridge 81, the arc-heel ridge 83 a and thetoe-heel ridge 83 b are preferably 0.125 inch above the surfaces 71 aand 71 b of the recesses 85 a and 85 b. This structure of the soleportion 28 moves mass to the perimeter of the body 22 and allows forgreater stabilization of the putter-type club head 20 during a putt by agolfer.

[0049] The crown portion 26 extends rearward from the face portion 24.The crown portion 26 has a central elongated section 44 and a frontsection 46. The front section 46 has a width w′ that extends from theheel end 23 to the toe end 25 of the face portion 24, and graduallynarrows as the front section 46 transitions into the central elongatedsection 44. The width, w′, preferably ranges from 2.5 inches to 4.5inches, more preferably from 3.0 inches to 3.75 inches, and mostpreferably 3.5 inches. The central elongated section 44 has a width w″that is less than the width w′ of the front section 46. The width, w″,preferably ranges from 1.0 inch to 3.0 inches, more preferably from 1.5inches to 2.25 inches, and most preferably 1.8 inches. The internalsurface 48 of the crown portion 26 partially defines the centralaperture 32. The crown portion preferably has a thickness that rangesfrom 0.10 inch to 0.50 inch, more preferably 0.15 inch to 0.30 inch.

[0050] The external surface 38 of the crown portion 26 preferably has analignment means 40 thereon. The external surface 38 also preferably hasa cylindrical rod 54 extending upward therefrom for engagement with ashaft, not shown. A preferred alignment means 40 is first and secondcircular inserts 40 a and 40 b disposed within first and second recesses42 a and 42 b in the crown portion 26. The depth of each of the recesses42 a and 42 b is preferably within 0.05 inch to 0.50 inch, morepreferably 0.1 inch to 0.250 inch. Each of the circular inserts 40 a and40 b preferably has a thickness ranging from 0.05 inch to 0.50 inch,more preferably 0.1 inch to 0.250 inch.

[0051] In a preferred embodiment, each of the circular inserts 40 a and40 b is composed of a thermosetting polyurethane material such asdescribed in U.S. Pat. No. 6,273,831, entitled Golf Club Head with APolymer Insert, assigned to Callaway Golf (the assignee of the PresentApplication), which is hereby incorporated by reference in its entirety.Each of the circular inserts 40 a and 40 b is preferably colored white,through painting or doping of the polyurethane with coloring agents, andeach circular insert 40 a and 40 b preferably has a texture of a golfball cover. Each of the circular inserts 40 a and 40 b preferably has adiameter ranging from 1.62 inches to 1.70 inches, and most preferably1.68 inches. Those skilled in the art will recognize that more than twocircular inserts 40 a and 40 b may be utilized without departing fromthe scope and spirit of the present invention. Alternative alignmentmeans are disclosed in U.S. Pat. No. 4,688,798, entitled Golf Club AndHead Including Alignment Indicators, assigned to Callaway Golf (theassignee of the Present Application), which pertinent parts are herebyincorporated by reference. As disclosed in U.S. Pat. No. 4,688,798, thealignment means assists a golfer in properly aiming a golf ball toward ahole when putting. Alternative alignment means, including a large whitestrip may be utilized in the present invention.

[0052] The face portion 24 preferably has a thickness ranging from 0.10inch to 0.50 inch, more preferably 0.20 inch to 0.35 inch. The faceportion 24 has an internal surface 60 that partially defines the centralaperture 32. The external surface 58 of the face preferably has a facerecess 52 therein with a face insert 50 disposed therein such asdisclosed in U.S. Pat. No. 6,238,302, entitled A Golf Club Head With AnInsert Having Integral Tabs, assigned to Callaway Golf (the assignee ofthe Present Application), which is hereby incorporated by reference inits entirety. As disclosed in U.S. Pat. No. 6,238,302, the face insertis preferably composed of a thermosetting polyurethane material and ispreferably colored white. In an alternative embodiment, the face portion24 is a non-insert blade as is known in the art.

[0053] The body 22 preferably has a length, L, from the face portion 24to the rearward most end of the aft mass portion 30 preferably rangingfrom 2.5 inches to 4.5 inches, more preferably from 3.0 inches to 3.5inches, and most preferably 3.25 inches. In one alternative embodiment,the body 22 has a length, L, that is equal to the width, w′.

[0054] One aspect of the club head 20 is the concentration of mass inthe center section 95 of the club head 20, as shown in FIG. 12. In apreferred embodiment, 210 grams to 250 grams of the mass of the clubhead 20 are located within the center section 95. In a most preferredembodiment, 232 grams of the mass of the club head 20 is located withinthe center section 95. Preferably 60% to 80% of the mass of the clubhead 20 are located within the center section 95.

[0055] As mentioned previously, the central aperture is defined by theinternal surface 60 of the face portion 24, the internal surface 48 ofthe crown portion 26, the internal surface 56 of the sole portion 28 andthe internal surface 62 of the aft-mass portion 30. The distance fromthe internal surface 48 of the crown portion 26 to the internal surface56 of the sole portion 28 preferably ranges from 0.01 inch to 1.50inches,. more preferably 0.25 inch to 1.0 inch, and most preferably 0.5inch. The distance from the internal surface 60 of the face portion 24to the internal surface 62 of the aft-mass portion 30 preferably rangesfrom 1.0 inch to 3.50 inches, more preferably from 1.5 inches to 3.0inches, and most preferably 1.87 inches. The body 22 is preferablyformed as a single cast structure using known investment castingtechniques. However, those skilled in the pertinent art will recognizethat alternative forming techniques such as milling, welding forged orformed pieces, and the like may be utilized without departing from thescope and spirit of the present invention.

[0056] The club head 20 preferably has a moment of inertia, Ixx, aboutan axis extending from the toe end 25 to the heel end 23 and through thecenter of gravity of 394.21 grams-centimeters squared. The club head 20preferably has a moment of inertia, Iyy, about an axis extending fromthe crown portion 26 to the sole portion 28 and the center of gravity of837.29 grams-centimeters squared. The club head 20 preferably has amoment of inertia, Izz, about an axis extending from the face portion 24to the aft-mass portion 30 and extending through the center of gravityof 547.48 grams-centimeters squared.

[0057] A preferred embodiment of a putter 100 is shown in FIGS. 18 and19, and an alternative embodiment is shown in FIGS. 20-21. FIGS. 18-21also illustrate a reference frame for measuring the center of gravity ofthe putter 100, which is different than the center of gravity for theclub head 20. The putter 100 generally includes the putter club head 20,a shaft 102 and a grip 104. In one embodiment, the putter 100 has aconventional club length that preferably ranges from 33 inches to 36inches, and a mass that preferably ranges from 475 grams to 525 grams.

[0058] In another embodiment, the putter 100 has a mid-club length thatpreferably ranges from 41 inches to 45 inches, and a mass thatpreferably ranges from 665 grams to 700 grams. In this mid-lengthembodiment, the shaft 102 preferably has a mass that ranges from 160grams to 175 grams and the grip 104 preferably has a mass that rangesfrom 135 grams to 145 grams. The loft angle is preferably three degreesand the lie angle is preferably 72 degrees.

[0059] In yet another embodiment, the putter 100 has a long-club lengththat preferably ranges from 46 inches to 50 inches, and a mass thatpreferably ranges from 730 grams to 775 grams. In this long-lengthembodiment, the shaft 102 preferably has a mass that ranges from 160grams to 175 grams. This long-length embodiment preferably has two grips104 (the second grip not shown) with the top grip 104 preferably havinga mass that ranges from 45 grams to 50 grams, and a bottom grip (notshown) having a mass that preferably ranges from 95 grams to 105 grams.The loft angle is preferably three degrees and the lie angle ispreferably 78 degrees. TABLE ONE Club Parameter 100 White Hot White HotName Units Pres. Inv. #1 #8 Description Total Mass Grams 497.8 496.8501.3 Total mass of club including head, shaft and grip Length Cm 34 3434 Nominal length of club Lie Angle Degrees 70 70 72 Xcg Cm −66.149−66.010 −64.915 Shaft Axis cg position Ycg Cm 0.150 0.824 2.224 CGoffset normal to the swing plane Zcg Cm −1.797 −0.946 −0.695 TargetDirection cg position Sx gm cm — — — Torsional Static Imbalance Sy gm cm−894.5 −470.0 −348.4 Swing Static Imbalance Sz gm cm 11332.5 11600.811116.3 Toe Down Static Imbalance Ixx Gm cm² 4622 3499 4293 TorsionalInertia Iyy Gm cm² 456130 470200 462440 Swing Inertia Izz Gm cm² 454990472810 465980 Toe Down Inertia Ixy Gm cm² 1975 9235 23639 Torsion/ToeDown Inertia Coupling Ixz Gm cm² −17065 −9471 −7275 Torsion/SwingInertia Coupling Iyz Gm cm² 130 223 653 Swing/Toe Down Inertia Coupling

[0060] In Table One, a putter 100 (conventional length) of the presentinvention is compared to two different ODYSSEY® WHITE HOT® putters. Xcg,Ycg and Zcg reference the location of the center of gravity of theputters. The static imbalance is a measure of the distance (parallel tothe ground) of the center of gravity of the putter 100 from the positionof the golfer's hands on the grip 104. One component of the staticimbalance is the swing static imbalance Sy, which is a result of thedistance of the center of gravity of the club head 20 is behind thegolfer's hands in the target direction. The putter 100 has a much larger(almost twice as much) swing static imbalance, Sy, then conventionalputters.

[0061] The location of the center of gravity of the putter 100 ismeasured using the reference frame through the straight portion of theshaft 102. The Xcg location is measured from the butt end of the shaft102. As shown in FIGS. 18-21, the center of gravity of the putter 100 islocated above the club head 20 and rearward from the face portion 24. Asshown in Table One, the Zcg location of the putter 100 is much furtherrearward than the conventional putters, 1.797 cm for the putter 100 ascompared to 0.946 cm and 0.695 cm for the conventional putters. It isbelieved that this rearward position of the center of gravity allows forthe putter 100 to have a much larger absolute product of inertia, Ixz (the torsion swing inertia) than the conventional putters, and a muchsmaller absolute product of inertia, Ixy (the torsion/toe down inertia)than the conventional putters. The products of inertia relate momentsabout one axis with club rotations about another axis. These clubrotations in turn effect the putting of a golf ball. A more detaileddiscussion is found in Beer, F. P., Johnston, E. R. Jr., VectorMechanics for Engineers 5th Edition, McGraw Hill, pp. 890-910, 1988,which is hereby incorporated by reference in its entirety.

[0062] From the foregoing it is believed that those skilled in thepertinent art will recognize the meritorious advancement of thisinvention and will readily understand that while the present inventionhas been described in association with a preferred embodiment thereof,and other embodiments illustrated in the accompanying drawings, numerouschanges, modifications and substitutions of equivalents may be madetherein without departing from the spirit and scope of this inventionwhich is intended to be unlimited by the foregoing except as may appearin the following appended claims. Therefore, the embodiments of theinvention in which an exclusive property or privilege is claimed aredefined in the following appended claims.

We claim as our invention:
 1. A putter comprising: a club head; a shaftconnected the club head; and a grip attached to shaft; wherein theputter has a swing static imbalance, Sy, greater than 500grams-centimeter.
 2. The putter according to claim 1 wherein the clubhead comprises: a body having a face portion, a crown portion, a soleportion and an aft-mass portion, wherein the face portion, the crownportion, the sole portion and the aft-mass portion define a centralaperture through the body having a heel end opening and a toe endopening, wherein the crown portion extends rearward from the faceportion to over the aft-mass portion, wherein the sole portion extendsfrom face portion to the aft-mass portion, and wherein the centralaperture separates the crown portion from the sole portion and the faceportion from the aft-mass portion.
 3. The putter according to claim 1wherein the club head comprises: a face portion having a recess with aface insert disposed therein; a sole portion extending rearward from theface portion, the sole portion having an internal surface and anexternal surface, the internal surface of the sole having a visible heelsection and a visible to section; an aft mass portion rearward from theface portion a distance of between 2.5 inches to 4.5 inches; a crownportion extending rearward from the face portion, the crown portionhaving a central elongated section extending over the aft mass portionand a forward section having a width from a heel end of the face portionto a toe end of the face portion from between 3.0 inches to 5.0 inches,the forward section having a width greater than a width of the centralelongated portion; and an alignment means disposed on an externalsurface of the crown portion.
 4. The putter according to claim 1 whereinthe club head comprises: a face portion; a crown portion having a frontsection and a central elongated section extending rearward from thefront section, the front section having a width from a heel end of theputter-type club head to a toe end of the putter-type club head rangingfrom 3.0 inches to 5.0 inches, the central elongated section having awidth ranging from 1.0 inch to 3.0 inches, the front section having awidth greater than a width of the central elongated section; a soleportion extending rearward from the face portion; an aft mass portiondisposed at a rearward end of the sole portion; and an alignment meansdisposed on an external surface of the crown portion; wherein theputter-type club head has length from the face portion to a rearwardmost end of the aft mass portion ranging from 2.5 inches to 4.5 inches.5. A putter comprising: a club head; a shaft connected the club head;and a grip attached to shaft; wherein the putter has a torsion swinginertia, Ixz, that has an absolute value, greater than 10,000grams-centimeter square.
 6. The putter according to claim 5 wherein theclub head comprises: a body having a face portion, a crown portion, asole portion and an aft-mass portion, wherein the face portion, thecrown portion, the sole portion and the aft-mass portion define acentral aperture through the body having a heel end opening and a toeend opening, wherein the crown portion extends rearward from the faceportion to over the aft-mass portion, wherein the sole portion extendsfrom face portion to the aft-mass portion, and wherein the centralaperture separates the crown portion from the sole portion and the faceportion from the aft-mass portion.
 7. The putter according to claim 5wherein the club head comprises: a face portion having a recess with aface insert disposed therein; a sole portion extending rearward from theface portion, the sole portion having an internal surface and anexternal surface, the internal surface of the sole having a visible heelsection and a visible to section; an aft mass portion rearward from theface portion a distance of between 2.5 inches to 4.5 inches; a crownportion extending rearward from the face portion, the crown portionhaving a central elongated section extending over the aft mass portionand a forward section having a width from a heel end of the face portionto a toe end of the face portion from between 3.0 inches to 5.0 inches,the forward section having a width greater than a width of the centralelongated portion; and an alignment means disposed on an externalsurface of the crown portion.
 8. The putter according to claim 5 whereinthe club head comprises: a face portion; a crown portion having a frontsection and a central elongated section extending rearward from thefront section, the front section having a width from a heel end of theputter-type club head to a toe end of the putter-type club head rangingfrom 3.0 inches to 5.0 inches, the central elongated section having awidth ranging from 1.0 inch to 3.0 inches, the front section having awidth greater than a width of the central elongated section; a soleportion extending rearward from the face portion; an aft mass portiondisposed at a rearward end of the sole portion; and an alignment meansdisposed on an external surface of the crown portion; wherein theputter-type club head has length from the face portion to a rearwardmost end of the aft mass portion ranging from 2.5 inches to 4.5 inches.9. A putter comprising: a club head; a shaft connected the club head;and a grip attached to shaft; wherein the putter has a center of gravitylocated at least 1.5 centimeters rearward from a shaft axis of theputter.
 10. The putter according to claim 9 wherein the club headcomprises: a body having a face portion, a crown portion, a sole portionand an aft-mass portion, wherein the face portion, the crown portion,the sole portion and the aft-mass portion define a central aperturethrough the body having a heel end opening and a toe end opening,wherein the crown portion extends rearward from the face portion to overthe aft-mass portion, wherein the sole portion extends from face portionto the aft-mass portion, and wherein the central aperture separates thecrown portion from the sole portion and the face portion from theaft-mass portion.
 11. The putter according to claim 9 wherein the clubhead comprises: a face portion having a recess with a face insertdisposed therein; a sole portion extending rearward from the faceportion, the sole portion having an internal surface and an externalsurface, the internal surface of the sole having a visible heel sectionand a visible to section; an aft mass portion rearward from the faceportion a distance of between 2.5 inches to 4.5 inches; a crown portionextending rearward from the face portion, the crown portion having acentral elongated section extending over the aft mass portion and aforward section having a width from a heel end of the face portion to atoe end of the face portion from between 3.0 inches to 5.0 inches, theforward section having a width greater than a width of the centralelongated portion; and an alignment means disposed on an externalsurface of the crown portion.
 12. The putter according to claim 9wherein the club head comprises: a face portion; a crown portion havinga front section and a central elongated section extending rearward fromthe front section, the front section having a width from a heel end ofthe putter-type club head to a toe end of the putter-type club headranging from 3.0 inches to 5.0 inches, the central elongated sectionhaving a width ranging from 1.0 inch to 3.0 inches, the front sectionhaving a width greater than a width of the central elongated section; asole portion extending rearward from the face portion; an aft massportion disposed at a rearward end of the sole portion; and an alignmentmeans disposed on an external surface of the crown portion; wherein theputter-type club head has length from the face portion to a rearwardmost end of the aft mass portion ranging from 2.5 inches to 4.5 inches.13. A putter comprising: a club head; a shaft connected the club head;and a grip attached to shaft; wherein the club head has at least 70percent of its mass located in a center section.
 14. The putteraccording to claim 13 wherein the club head comprises: a body having aface portion, a crown portion, a sole portion and an aft-mass portion,wherein the face portion, the crown portion, the sole portion and theaft-mass portion define a central aperture through the body having aheel end opening and a toe end opening, wherein the crown portionextends rearward from the face portion to over the aft-mass portion,wherein the sole portion extends from face portion to the aft-massportion, and wherein the central aperture separates the crown portionfrom the sole portion and the face portion from the aft-mass portion.15. The putter according to claim 13 wherein the club head comprises: aface portion having a recess with a face insert disposed therein; a soleportion extending rearward from the face portion, the sole portionhaving an internal surface and an external surface, the internal surfaceof the sole having a visible heel section and a visible to section; anaft mass portion rearward from the face portion a distance of between2.5 inches to 4.5 inches; a crown portion extending rearward from theface portion, the crown portion having a central elongated sectionextending over the aft mass portion and a forward section having a widthfrom a heel end of the face portion to a toe end of the face portionfrom between 3.0 inches to 5.0 inches, the forward section having awidth greater than a width of the central elongated portion; and analignment means disposed on an external surface of the crown portion.16. The putter according to claim 13 wherein the club head comprises: aface portion; a crown portion having a front section and a centralelongated section extending rearward from the front section, the frontsection having a width from a heel end of the putter-type club head to atoe end of the putter-type club head ranging from 3.0 inches to 5.0inches, the central elongated section having a width ranging from 1.0inch to 3.0 inches, the front section having a width greater than awidth of the central elongated section; a sole portion extendingrearward from the face portion; an aft mass portion disposed at arearward end of the sole portion; and an alignment means disposed on anexternal surface of the crown portion; wherein the putter-type club headhas length from the face portion to a rearward most end of the aft massportion ranging from 2.5 inches to 4.5 inches.
 17. The putter accordingto claim 16 wherein the central section is defined by the width of thecentral elongated section.